Why do salmon swim upstream?
Show answer & explanation
Answer: Spawning in birthplace
Escaping ocean predators — Wrong. Ocean has predators, but upstream migration is for reproduction—returning to natal streams to spawn.
Spawning in birthplace ✓ — Correct! Natal homing! Salmon return to birthplace to spawn: (1) Imprinting—remember birth stream's chemical signature. (2) Olfactory navigation—follow scent upstream. (3) best conditions—gravel beds for eggs. Incredible journey: hundreds of miles, swimming against current, jumping waterfalls. Anadromous life cycle—born in freshwater, mature in ocean, return to spawn. Most Pacific salmon die after spawning (semelparous). Exhausting migration—use all energy reserves. Magnetic sense aids ocean navigation!
Searching for more food — Wrong. Salmon don't feed during spawning migration—use stored energy. Upstream journey is reproduction-driven, not foraging.
More Animal Behavior questions
- Why can the same soft barn-owl feathers that mute flight make rainy hunting worse?
- Why is silent flight useful even if a mouse never hears the owl coming?
- Owl wing velvet may quiet a sound most airfoil diagrams ignore. Which one?
- At high wing angles, why can an owl's front-edge combs make airflow quieter?
- A barn owl can glide slowly without much wingbeat. What quiets flight before feather tricks?
- A platypus lays eggs but feeds hatchlings milk without nipples. What makes that less contradictory?